Question

Which of the following can not be the probability of an event ?

• A. $\frac{39}{100}$
• B. $\frac{0.001}{20}$
• C. $\frac{10}{0.2}$
• D. $10\%$

Hint:

Always simplify fractions and percentages first.
Any value greater than $1$ (or $100\%$) or less than $0$ can never represent a probability.

Answer 1

The Correct Option is C

Step 1: Remember the golden rule of probability.
Any probability value must satisfy $0 \le P(E) \le 1$; nothing outside this range is allowed.
Step 2: Quickly convert each option to a decimal.
(A) $\frac{39}{100}=0.39$, (B) $\frac{0.001}{20}=0.00005$, (C) $\frac{10}{0.2}=50$, (D) $10\%=0.1$.
Step 3: Pick out the value that breaks the rule.
Only option (C), $50$, is far greater than $1$, so it cannot be a probability.
Step 4: Conclude.
\[ \boxed{\frac{10}{0.2} = 50} \]